#2 cylinder running rich

I have diagnosed that my #2 cylinder is running rich. The top of the piston has a lot more carbon than the others, and the new exhaust I installed is turning 3x more black than the other side. It also sounds like it's missing.

So my #2 cylinder is running rich.....what do I have to do???

Valves adjusted?
Steve

swest wrote: Valves adjusted?
Steve

No.... :blush:

That's where you start.
Steve

Since it's the #2 cylinder I would check this first......

I'm assuming your bike has the stock vacuum operated petcock. If so, it may have a faulty diaphragm. A faulty petcock diaphragm often allows fuel to be drawn through the vacuum tube that runs from the petcock to the #2 carb. When that happens #2 cylinder runs rich or may foul. I suggest you pull the vacuum tube off the #2 carb and check to see if it is wet with fuel; it should not be. Also, you can disconnect that vacuum tube; cap the #2 carb vacuum port; and cap the vacuum port on the petcock. Then run the bike with the petcock set to the "prime" position and see if #2 cylinder no longer runs rich. If you find that to be the problem you can rebuild the petcock or replace it. Ed

swest wrote: That's where you start.
Steve

I was really hoping not to have to go through another valve gasket replacement again. (I'm on my 3rd one now)

So I'm doing a valve job, which alone will take a week to ten days of waiting for the proper spacers to come in the mail (assuming I can find the right spacers on eBay at all). Then I'll be tearing the engine down again to the head gasket to replace the cam chain guides. Then I'm guessing I'll be fiddling with the carburators, probably screwing them up good trying to figure out this rich cylinder business. Seems everything I touch on this engine causes something else to break. :dry: This is the first bike I've ever worked on.

By the way, I got an NOS chain guide...are they supposed to be made of soft rubber??? Thought that was kinda weird as the other replacement parts I got were hard.

I highly recommend that as a first step you check the petcock vacuum tube as I described. That is a frequent cause of #2 cylinder running rich on bikes with your type petcock. Ed

650ed wrote: I highly recommend that as a first step you check the petcock vacuum tube as I described. That is a frequent cause of #2 cylinder running rich on bikes with your type petcock. Ed

By diaphragm, you mean the rubber plate with like 5 holes in it? Didn't read your comment until after replying to swest.

Hopefully I can check this out after work, thanks!

Ed is right, check that first. A valve adjustment is just taking the valve cover off and adjusting them. eBay isn't the only place to get shims.
Steve
jetsrus.com/valve/valve_shims.html

Float levels checked, utilizing the "clear-tube" method? :whistle:

Thought it'd be nice to post what I found on top of the pistons with the endoscope.
Lets start off with the problem child....cylinder 2







Next, cylinder 1 looked like it was leaking some serious oil or something. The black stuff on the side the bike leans when parked.



Cylinder 3 was remarkably clean other than one tiny blotch of black.



And cylinder 4...also remarkably clean short of a small blotch.

Valve guide seals. Not bad for a 30 year old bike.
Steve